linux/block/blk.h
Yu Kuai e5d98cc331 block: support to account io_ticks precisely
[ Upstream commit 99dc422335 ]

Currently, io_ticks is accounted based on sampling, specifically
update_io_ticks() will always account io_ticks by 1 jiffies from
bdev_start_io_acct()/blk_account_io_start(), and the result can be
inaccurate, for example(HZ is 250):

Test script:
fio -filename=/dev/sda -bs=4k -rw=write -direct=1 -name=test -thinktime=4ms

Test result: util is about 90%, while the disk is really idle.

This behaviour is introduced by commit 5b18b5a737 ("block: delete
part_round_stats and switch to less precise counting"), however, there
was a key point that is missed that this patch also improve performance
a lot:

Before the commit:
part_round_stats:
  if (part->stamp != now)
   stats |= 1;

  part_in_flight()
  -> there can be lots of task here in 1 jiffies.
  part_round_stats_single()
   __part_stat_add()
  part->stamp = now;

After the commit:
update_io_ticks:
  stamp = part->bd_stamp;
  if (time_after(now, stamp))
   if (try_cmpxchg())
    __part_stat_add()
    -> only one task can reach here in 1 jiffies.

Hence in order to account io_ticks precisely, we only need to know if
there are IO inflight at most once in one jiffies. Noted that for
rq-based device, iterating tags should not be used here because
'tags->lock' is grabbed in blk_mq_find_and_get_req(), hence
part_stat_lock_inc/dec() and part_in_flight() is used to trace inflight.
The additional overhead is quite little:

 - per cpu add/dec for each IO for rq-based device;
 - per cpu sum for each jiffies;

And it's verified by null-blk that there are no performance degration
under heavy IO pressure.

Fixes: 5b18b5a737 ("block: delete part_round_stats and switch to less precise counting")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240509123717.3223892-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-06-12 11:11:35 +02:00

523 lines
16 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BLK_INTERNAL_H
#define BLK_INTERNAL_H
#include <linux/blk-crypto.h>
#include <linux/memblock.h> /* for max_pfn/max_low_pfn */
#include <xen/xen.h>
#include "blk-crypto-internal.h"
struct elevator_type;
/* Max future timer expiry for timeouts */
#define BLK_MAX_TIMEOUT (5 * HZ)
extern struct dentry *blk_debugfs_root;
struct blk_flush_queue {
spinlock_t mq_flush_lock;
unsigned int flush_pending_idx:1;
unsigned int flush_running_idx:1;
blk_status_t rq_status;
unsigned long flush_pending_since;
struct list_head flush_queue[2];
unsigned long flush_data_in_flight;
struct request *flush_rq;
};
bool is_flush_rq(struct request *req);
struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
gfp_t flags);
void blk_free_flush_queue(struct blk_flush_queue *q);
void blk_freeze_queue(struct request_queue *q);
void __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic);
void blk_queue_start_drain(struct request_queue *q);
int __bio_queue_enter(struct request_queue *q, struct bio *bio);
void submit_bio_noacct_nocheck(struct bio *bio);
static inline bool blk_try_enter_queue(struct request_queue *q, bool pm)
{
rcu_read_lock();
if (!percpu_ref_tryget_live_rcu(&q->q_usage_counter))
goto fail;
/*
* The code that increments the pm_only counter must ensure that the
* counter is globally visible before the queue is unfrozen.
*/
if (blk_queue_pm_only(q) &&
(!pm || queue_rpm_status(q) == RPM_SUSPENDED))
goto fail_put;
rcu_read_unlock();
return true;
fail_put:
blk_queue_exit(q);
fail:
rcu_read_unlock();
return false;
}
static inline int bio_queue_enter(struct bio *bio)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
if (blk_try_enter_queue(q, false))
return 0;
return __bio_queue_enter(q, bio);
}
#define BIO_INLINE_VECS 4
struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs,
gfp_t gfp_mask);
void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned short nr_vecs);
bool bvec_try_merge_hw_page(struct request_queue *q, struct bio_vec *bv,
struct page *page, unsigned len, unsigned offset,
bool *same_page);
static inline bool biovec_phys_mergeable(struct request_queue *q,
struct bio_vec *vec1, struct bio_vec *vec2)
{
unsigned long mask = queue_segment_boundary(q);
phys_addr_t addr1 = page_to_phys(vec1->bv_page) + vec1->bv_offset;
phys_addr_t addr2 = page_to_phys(vec2->bv_page) + vec2->bv_offset;
/*
* Merging adjacent physical pages may not work correctly under KMSAN
* if their metadata pages aren't adjacent. Just disable merging.
*/
if (IS_ENABLED(CONFIG_KMSAN))
return false;
if (addr1 + vec1->bv_len != addr2)
return false;
if (xen_domain() && !xen_biovec_phys_mergeable(vec1, vec2->bv_page))
return false;
if ((addr1 | mask) != ((addr2 + vec2->bv_len - 1) | mask))
return false;
return true;
}
static inline bool __bvec_gap_to_prev(const struct queue_limits *lim,
struct bio_vec *bprv, unsigned int offset)
{
return (offset & lim->virt_boundary_mask) ||
((bprv->bv_offset + bprv->bv_len) & lim->virt_boundary_mask);
}
/*
* Check if adding a bio_vec after bprv with offset would create a gap in
* the SG list. Most drivers don't care about this, but some do.
*/
static inline bool bvec_gap_to_prev(const struct queue_limits *lim,
struct bio_vec *bprv, unsigned int offset)
{
if (!lim->virt_boundary_mask)
return false;
return __bvec_gap_to_prev(lim, bprv, offset);
}
static inline bool rq_mergeable(struct request *rq)
{
if (blk_rq_is_passthrough(rq))
return false;
if (req_op(rq) == REQ_OP_FLUSH)
return false;
if (req_op(rq) == REQ_OP_WRITE_ZEROES)
return false;
if (req_op(rq) == REQ_OP_ZONE_APPEND)
return false;
if (rq->cmd_flags & REQ_NOMERGE_FLAGS)
return false;
if (rq->rq_flags & RQF_NOMERGE_FLAGS)
return false;
return true;
}
/*
* There are two different ways to handle DISCARD merges:
* 1) If max_discard_segments > 1, the driver treats every bio as a range and
* send the bios to controller together. The ranges don't need to be
* contiguous.
* 2) Otherwise, the request will be normal read/write requests. The ranges
* need to be contiguous.
*/
static inline bool blk_discard_mergable(struct request *req)
{
if (req_op(req) == REQ_OP_DISCARD &&
queue_max_discard_segments(req->q) > 1)
return true;
return false;
}
static inline unsigned int blk_rq_get_max_segments(struct request *rq)
{
if (req_op(rq) == REQ_OP_DISCARD)
return queue_max_discard_segments(rq->q);
return queue_max_segments(rq->q);
}
static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
enum req_op op)
{
if (unlikely(op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE))
return min(q->limits.max_discard_sectors,
UINT_MAX >> SECTOR_SHIFT);
if (unlikely(op == REQ_OP_WRITE_ZEROES))
return q->limits.max_write_zeroes_sectors;
return q->limits.max_sectors;
}
#ifdef CONFIG_BLK_DEV_INTEGRITY
void blk_flush_integrity(void);
bool __bio_integrity_endio(struct bio *);
void bio_integrity_free(struct bio *bio);
static inline bool bio_integrity_endio(struct bio *bio)
{
if (bio_integrity(bio))
return __bio_integrity_endio(bio);
return true;
}
bool blk_integrity_merge_rq(struct request_queue *, struct request *,
struct request *);
bool blk_integrity_merge_bio(struct request_queue *, struct request *,
struct bio *);
static inline bool integrity_req_gap_back_merge(struct request *req,
struct bio *next)
{
struct bio_integrity_payload *bip = bio_integrity(req->bio);
struct bio_integrity_payload *bip_next = bio_integrity(next);
return bvec_gap_to_prev(&req->q->limits,
&bip->bip_vec[bip->bip_vcnt - 1],
bip_next->bip_vec[0].bv_offset);
}
static inline bool integrity_req_gap_front_merge(struct request *req,
struct bio *bio)
{
struct bio_integrity_payload *bip = bio_integrity(bio);
struct bio_integrity_payload *bip_next = bio_integrity(req->bio);
return bvec_gap_to_prev(&req->q->limits,
&bip->bip_vec[bip->bip_vcnt - 1],
bip_next->bip_vec[0].bv_offset);
}
extern const struct attribute_group blk_integrity_attr_group;
#else /* CONFIG_BLK_DEV_INTEGRITY */
static inline bool blk_integrity_merge_rq(struct request_queue *rq,
struct request *r1, struct request *r2)
{
return true;
}
static inline bool blk_integrity_merge_bio(struct request_queue *rq,
struct request *r, struct bio *b)
{
return true;
}
static inline bool integrity_req_gap_back_merge(struct request *req,
struct bio *next)
{
return false;
}
static inline bool integrity_req_gap_front_merge(struct request *req,
struct bio *bio)
{
return false;
}
static inline void blk_flush_integrity(void)
{
}
static inline bool bio_integrity_endio(struct bio *bio)
{
return true;
}
static inline void bio_integrity_free(struct bio *bio)
{
}
#endif /* CONFIG_BLK_DEV_INTEGRITY */
unsigned long blk_rq_timeout(unsigned long timeout);
void blk_add_timer(struct request *req);
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
unsigned int nr_segs);
bool blk_bio_list_merge(struct request_queue *q, struct list_head *list,
struct bio *bio, unsigned int nr_segs);
/*
* Plug flush limits
*/
#define BLK_MAX_REQUEST_COUNT 32
#define BLK_PLUG_FLUSH_SIZE (128 * 1024)
/*
* Internal elevator interface
*/
#define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)
bool blk_insert_flush(struct request *rq);
int elevator_switch(struct request_queue *q, struct elevator_type *new_e);
void elevator_disable(struct request_queue *q);
void elevator_exit(struct request_queue *q);
int elv_register_queue(struct request_queue *q, bool uevent);
void elv_unregister_queue(struct request_queue *q);
ssize_t part_size_show(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t part_stat_show(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t part_fail_show(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t part_fail_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count);
ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
ssize_t part_timeout_store(struct device *, struct device_attribute *,
const char *, size_t);
static inline bool bio_may_exceed_limits(struct bio *bio,
const struct queue_limits *lim)
{
switch (bio_op(bio)) {
case REQ_OP_DISCARD:
case REQ_OP_SECURE_ERASE:
case REQ_OP_WRITE_ZEROES:
return true; /* non-trivial splitting decisions */
default:
break;
}
/*
* All drivers must accept single-segments bios that are <= PAGE_SIZE.
* This is a quick and dirty check that relies on the fact that
* bi_io_vec[0] is always valid if a bio has data. The check might
* lead to occasional false negatives when bios are cloned, but compared
* to the performance impact of cloned bios themselves the loop below
* doesn't matter anyway.
*/
return lim->chunk_sectors || bio->bi_vcnt != 1 ||
bio->bi_io_vec->bv_len + bio->bi_io_vec->bv_offset > PAGE_SIZE;
}
struct bio *__bio_split_to_limits(struct bio *bio,
const struct queue_limits *lim,
unsigned int *nr_segs);
int ll_back_merge_fn(struct request *req, struct bio *bio,
unsigned int nr_segs);
bool blk_attempt_req_merge(struct request_queue *q, struct request *rq,
struct request *next);
unsigned int blk_recalc_rq_segments(struct request *rq);
void blk_rq_set_mixed_merge(struct request *rq);
bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);
void blk_set_default_limits(struct queue_limits *lim);
int blk_dev_init(void);
/*
* Contribute to IO statistics IFF:
*
* a) it's attached to a gendisk, and
* b) the queue had IO stats enabled when this request was started
*/
static inline bool blk_do_io_stat(struct request *rq)
{
return (rq->rq_flags & RQF_IO_STAT) && !blk_rq_is_passthrough(rq);
}
void update_io_ticks(struct block_device *part, unsigned long now, bool end);
unsigned int part_in_flight(struct block_device *part);
static inline void req_set_nomerge(struct request_queue *q, struct request *req)
{
req->cmd_flags |= REQ_NOMERGE;
if (req == q->last_merge)
q->last_merge = NULL;
}
/*
* Internal io_context interface
*/
struct io_cq *ioc_find_get_icq(struct request_queue *q);
struct io_cq *ioc_lookup_icq(struct request_queue *q);
#ifdef CONFIG_BLK_ICQ
void ioc_clear_queue(struct request_queue *q);
#else
static inline void ioc_clear_queue(struct request_queue *q)
{
}
#endif /* CONFIG_BLK_ICQ */
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
const char *page, size_t count);
extern void blk_throtl_bio_endio(struct bio *bio);
extern void blk_throtl_stat_add(struct request *rq, u64 time);
#else
static inline void blk_throtl_bio_endio(struct bio *bio) { }
static inline void blk_throtl_stat_add(struct request *rq, u64 time) { }
#endif
struct bio *__blk_queue_bounce(struct bio *bio, struct request_queue *q);
static inline bool blk_queue_may_bounce(struct request_queue *q)
{
return IS_ENABLED(CONFIG_BOUNCE) &&
q->limits.bounce == BLK_BOUNCE_HIGH &&
max_low_pfn >= max_pfn;
}
static inline struct bio *blk_queue_bounce(struct bio *bio,
struct request_queue *q)
{
if (unlikely(blk_queue_may_bounce(q) && bio_has_data(bio)))
return __blk_queue_bounce(bio, q);
return bio;
}
#ifdef CONFIG_BLK_DEV_ZONED
void disk_free_zone_bitmaps(struct gendisk *disk);
void disk_clear_zone_settings(struct gendisk *disk);
int blkdev_report_zones_ioctl(struct block_device *bdev, unsigned int cmd,
unsigned long arg);
int blkdev_zone_mgmt_ioctl(struct block_device *bdev, blk_mode_t mode,
unsigned int cmd, unsigned long arg);
#else /* CONFIG_BLK_DEV_ZONED */
static inline void disk_free_zone_bitmaps(struct gendisk *disk) {}
static inline void disk_clear_zone_settings(struct gendisk *disk) {}
static inline int blkdev_report_zones_ioctl(struct block_device *bdev,
unsigned int cmd, unsigned long arg)
{
return -ENOTTY;
}
static inline int blkdev_zone_mgmt_ioctl(struct block_device *bdev,
blk_mode_t mode, unsigned int cmd, unsigned long arg)
{
return -ENOTTY;
}
#endif /* CONFIG_BLK_DEV_ZONED */
struct block_device *bdev_alloc(struct gendisk *disk, u8 partno);
void bdev_add(struct block_device *bdev, dev_t dev);
int blk_alloc_ext_minor(void);
void blk_free_ext_minor(unsigned int minor);
#define ADDPART_FLAG_NONE 0
#define ADDPART_FLAG_RAID 1
#define ADDPART_FLAG_WHOLEDISK 2
int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
sector_t length);
int bdev_del_partition(struct gendisk *disk, int partno);
int bdev_resize_partition(struct gendisk *disk, int partno, sector_t start,
sector_t length);
void drop_partition(struct block_device *part);
void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors);
struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
struct lock_class_key *lkclass);
int bio_add_hw_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset,
unsigned int max_sectors, bool *same_page);
/*
* Clean up a page appropriately, where the page may be pinned, may have a
* ref taken on it or neither.
*/
static inline void bio_release_page(struct bio *bio, struct page *page)
{
if (bio_flagged(bio, BIO_PAGE_PINNED))
unpin_user_page(page);
}
struct request_queue *blk_alloc_queue(int node_id);
int disk_scan_partitions(struct gendisk *disk, blk_mode_t mode);
int disk_alloc_events(struct gendisk *disk);
void disk_add_events(struct gendisk *disk);
void disk_del_events(struct gendisk *disk);
void disk_release_events(struct gendisk *disk);
void disk_block_events(struct gendisk *disk);
void disk_unblock_events(struct gendisk *disk);
void disk_flush_events(struct gendisk *disk, unsigned int mask);
extern struct device_attribute dev_attr_events;
extern struct device_attribute dev_attr_events_async;
extern struct device_attribute dev_attr_events_poll_msecs;
extern struct attribute_group blk_trace_attr_group;
blk_mode_t file_to_blk_mode(struct file *file);
int truncate_bdev_range(struct block_device *bdev, blk_mode_t mode,
loff_t lstart, loff_t lend);
long blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg);
long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg);
extern const struct address_space_operations def_blk_aops;
int disk_register_independent_access_ranges(struct gendisk *disk);
void disk_unregister_independent_access_ranges(struct gendisk *disk);
#ifdef CONFIG_FAIL_MAKE_REQUEST
bool should_fail_request(struct block_device *part, unsigned int bytes);
#else /* CONFIG_FAIL_MAKE_REQUEST */
static inline bool should_fail_request(struct block_device *part,
unsigned int bytes)
{
return false;
}
#endif /* CONFIG_FAIL_MAKE_REQUEST */
/*
* Optimized request reference counting. Ideally we'd make timeouts be more
* clever, as that's the only reason we need references at all... But until
* this happens, this is faster than using refcount_t. Also see:
*
* abc54d634334 ("io_uring: switch to atomic_t for io_kiocb reference count")
*/
#define req_ref_zero_or_close_to_overflow(req) \
((unsigned int) atomic_read(&(req->ref)) + 127u <= 127u)
static inline bool req_ref_inc_not_zero(struct request *req)
{
return atomic_inc_not_zero(&req->ref);
}
static inline bool req_ref_put_and_test(struct request *req)
{
WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
return atomic_dec_and_test(&req->ref);
}
static inline void req_ref_set(struct request *req, int value)
{
atomic_set(&req->ref, value);
}
static inline int req_ref_read(struct request *req)
{
return atomic_read(&req->ref);
}
#endif /* BLK_INTERNAL_H */